Of course you should. You’re the wife, you’re his stepmom, and you care about him. Of course you should sign it.
If the mother rejects the card and you get it sent back, keep it. If she takes the card and never gives it to him, keep track of the time and date you sent it so as your SS gets older, you can answer questions if he asks.
Another thought, keep a journal. You and your husband. About how much you miss him, about what you’d like to do if he were there, etc, etc.
When you’re not part of a child’s life, they only go by what they’re told. And when that’s all they’ve heard all their life, it’s hard to change their minds until they see things for themselves. If you guys truly love this little boy, then try to show it one way or another and keep track. So when he’s old enough, you can show him you tried.
** ADD **
LOL! Christian and Caitlyn’s Mom….you kill me.
Do aunts and uncles send your kids cards? Do you have close friends that attend birthday parties for your kids? Or are they not allowed to attend the party, buy a gift, or sign a card, simply because they’re “not Mom”??
Really? That must suck for your children.
Mom and stepmom - I've been there